The MFJ-752C is a dual tunable audio filter that permits you to zero in on a single sideband and Morse code signal and notch out interference at the same time. It can also be used for AM mode shortwave listening. The primary filter has tunable peak, notch, lowpass and highpass. Auxiliary filter has peak and notch. The filter is automatically bypassed when the unit is off. Speaker and phone jacks are provided.